Influence of the colonic environment on duodenal G-cell activity and proliferation

To investigate the effects of the colonic environment on duodenal G-cell activity and proliferation, thirty white rats underwent antrectomy with gastroduodenostomy (control group) or antrectomy with interposition of a 15 mm segment of transverse colon between the gastric fundus and the first duodenal portion (experimental group). Three to four months after surgery, serum gastrin determinations were carried out by radioimmunoassay either in fasted or freely fed rats. The duodenum was then removed and its proximal third was used for G-cell count (immuno-peroxidase method) and for assessment of G-cell cytoplasmic granule content (electron microscopy examination). The interposition of a colonic segment between the gastric fundus and the first duodenal portion did not affect either serum gastrin levels or the cytoplasmic granule content of duodenal G-cells, while significantly increasing duodenal G-cell density. These results indicate that the colonic environment enhances duodenal G-cell proliferation, but gastrin release from the enlarged duodenal G-cell mass is not stimulated by the interposition of a colonic segment to replace the antrum, either under fasting or feeding conditions.